Coronary sinus lead delivery catheter

ABSTRACT

A guide catheter for accessing the coronary sinus ostium has a proximal portion and a distal portion formed into a preformed shape including a curved segment. The preformed shape includes a first arc, a second arc, a third arc, a fourth arc, and a generally straight terminal portion. The preformed shape is generally a J-shape, having a terminal portion generally parallel to the proximal portion, a generally closed arc or a generally open arc.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/916,353, titled “CORONARY SINUS LEAD DELIVERY CATHETER,” filed Aug.11, 2004, which is incorporated herein by reference in its entirety.

This application is also related to co-pending and commonly-assignedU.S. patent application Ser. No. 11/733,919, titled “CORONARY SINUS LEADDELIVERY CATHETER,” filed Apr. 11, 2007 and also to co-pending andcommonly-assigned U.S. patent application Ser. No. 10/916,148, titled“RIGHT-SIDE CORONARY SINUS LEAD DELIVERY CATHETER,” filed on Aug. 11,2004, both of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

This invention relates to cardiovascular guide catheters and methods ofusing the catheters. More specifically, it relates to a guide catheterfor locating and cannulating the coronary sinus.

BACKGROUND

Guiding catheters are instruments that allow a physician to access andcannulate vessels in a patient's heart for conducting various medicalprocedures, including venography and implantation of cardiac leads.Cannulating heart vessels requires navigating a small-diameter flexibleguide catheter through the tortuous vasculature into a heart chamber,and then into a destination heart vessel. Once the destination heartvessel is reached, the catheter acts as a conduit for insertion ofpayloads, for example pacing leads, into the vessel.

Guiding catheter systems are often configured with a pre-shaped profilethat is optimized for the intended vessel destination. One commonlyaccessed destination vessel for placement of cardiac pacing leads is thecoronary sinus. Typically, access to the coronary sinus is gainedthrough the left subclavian vein. The coronary sinus may also beaccessed through the right subclavian vein.

There is a need for a lead delivery system and method to allow accurateand rapid lead implantation and anchoring in the coronary sinus orsub-branches of the coronary sinus.

SUMMARY

The present invention, according to one embodiment, is a guide catheterfor accessing the coronary sinus. The guide catheter includes a flexibleelongate shaft having a proximal portion and a distal portion having apreformed shape. The preformed shape includes a first arc having a firstarc radius of from about 3.0 to about 4.0 inches, a second arc distallyadjacent the first arc and having a second arc radius of from about 1.2to about 1.8 inches, a third arc distally adjacent the second having athird arc radius of from about 2.2 to about 3.7 inches, and a fourth arcdistally adjacent the third arc having a fourth arc radius of from about1.0 to about 1.5 inches. The distal portion terminates in a generallystraight terminal portion adjacent the fourth arc and having a length offrom about 0.3 to about 1.9 inches. Optionally, the second arc and thethird arc are combined into a single middle arc having a middle arcradius of from about 2.2 to about 3.7 inches. According to oneembodiment, the preformed shape is generally a J-shape wherein theterminal portion is generally parallel to the proximal portion.According to another embodiment, the preformed shape is a generallyclosed arc. According to yet another embodiment, the preformed shape isa generally open arc.

The present invention, according to another embodiment, is a method ofcannulating the coronary sinus. The method includes providing a flexibleelongate shaft having a proximal portion and a distal portion andforming the distal portion into a preformed shape. The preformed shapeincludes a first arc having a first arc radius of from about 3.0 toabout 4.0 inches, a second arc distally adjacent the first arc having asecond arc radius of from about 1.2 to about 1.8 inches, a third arcdistally adjacent the second having a third arc radius of from about 2.2to about 3.7 inches, a fourth arc distally adjacent the third arc havinga fourth arc radius of from about 1.0 to about 1.5 inches and agenerally straight terminal portion distally adjacent the fourth arc andhaving a length of from about 0.3 to about 1.9 inches. The distalportion is inserted into an insertion vessel and the proximal portion ismanipulated so as to insert the distal portion into the coronary sinus.

According to one embodiment, manipulating the distal portion includesadvancing the distal portion through the superior vena cava, and intothe right atrium using the superior vena cava for support, until theterminal portion crosses the tricuspid valve. The distal portion istorqued 90 degrees counterclockwise to maneuver the terminal portioninto the same plane as the coronary sinus ostium. The distal portion iswithdrawn back into the right atrium while torque is maintained. Theterminal portion is advanced into the coronary sinus ostium whilemaintaining torque.

According to another embodiment, the method of cannulating the coronarysinus includes providing a guide wire and an inner catheter slidablewithin the shaft. The inner catheter is advanced through the guidecatheter, beyond the terminal portion, and torqued to located thecoronary sinus ostium. The guide wire is advanced through the innercatheter, and the guide wire and the inner catheter are alternatelyadvanced into the coronary sinus ostium. The terminal portion isadvanced over the inner catheter and into the coronary sinus ostium.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. As will be realized, theinvention is capable of modifications in various obvious aspects, allwithout departing from the spirit and scope of the present invention.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a catheter deployed in a heart and partsof the vascular system, according to one embodiment of the presentinvention.

FIG. 2 is a side view of a catheter according to one embodiment of thepresent invention.

FIG. 3 is a side view of a catheter according to another embodiment ofthe present invention.

FIG. 4 is a side view of a catheter according to yet another embodimentof the present invention.

FIG. 5 is a side view of a catheter assembly according to anotherembodiment of the present invention.

FIG. 6 is a schematic view of the catheter assembly of FIG. 5 deployedin the heart according to one embodiment of the present invention.

FIG. 7 is a flowchart depicting a method of accessing the coronary sinusaccording to one embodiment of the present invention.

FIG. 8 is a flowchart depicting a method of accessing the coronary sinusaccording to another embodiment of the present invention.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

FIG. 1 shows a catheter 10 deployed in a human heart 12 according to anembodiment of the present invention. As shown in FIG. 1, the heart 12includes a right atrium 14 and a right ventricle 16 separated by atricuspid valve 18. During normal operation of the heart 12,deoxygenated blood is fed into the right atrium 14 through the superiorvena cava 20 and the inferior vena cava 22. The major veins supplyingblood to the superior vena cava 20 include the right and left axillaryveins 24 and 26, which flow into the right and left subclavian veins 28and 30. The right and left external jugular 32 and 34, along with theright and left internal jugular 36 and 38, join the right and leftsubclavian veins 28 and 30 to form the right and left brachiocephalicveins 40 and 42. The right and left brachiocephalic veins 40 and 42combine to flow into the superior vena cava 20.

The catheter 10, shown in FIG. 1, includes a flexible, elongate shaft 48extending from a proximal end 50 to a distal portion 52. As shown inFIG. 1, the catheter 10 enters the vascular system through a wall of theleft subclavian vein 30, extends through the left brachiocephalic vein42 and the superior vena cava 20, and enters the right atrium 14. Asfurther shown, catheter 10 then enters the coronary sinus ostium 54 sothat the distal portion 52 of the catheter 10 is located in the coronarysinus 56. In other embodiments of the present invention, the catheter 10enters the vascular system through the left axillary vein 26, the leftexternal jugular 34, the left internal jugular 38, or the leftbrachiocephalic vein 42. The catheter 10 may be a guide catheter forassisting with placement of a cardiac pacing lead.

FIG. 2 illustrates a catheter 100 in accordance with a first embodimentof the present invention. As shown in FIG. 2, the catheter 100 has aproximal portion 102 and a distal portion 106. The proximal portion 102is manipulated by the surgeon to advance the distal portion 106 into thepatient's anatomy to access the coronary sinus 56. While the proximalportion 102 is generally straight, the distal portion 106 isadvantageously pre-shaped beginning at a deflection location 108,providing an optimized geometry for locating specific vascular features(e.g., the coronary sinus 56). The pre-shaped distal portion 106includes a series of arcs or curves.

As shown in FIG. 2, the distal portion 106 includes a first arc orcatheter segment 110, which is coupled to a second arc or cathetersegment 120. Extending from the distal end of the catheter segment 120is a third arc or catheter segment 130, which is coupled to a fourth arcor catheter segment 140. Extending from the distal end of the cathetersegment 140 is a generally straight end or terminal segment 160 having alength l. Optionally, the terminal segment 160 is not present. In oneembodiment, the distal portion 106 has a co-planar configuration suchthat the shaped curve lies in a plane. In one embodiment, the secondsegment 120 and third segment 130 are replaced with a combined arc orcatheter segment 150, as further discussed below.

The various catheter segments are shaped and angled relative to eachother to provide an elongate curvature to the distal portion 106. Toprovide the overall shape, each of the catheter segments 110, 120, 130,and 140 has a specific radius and arc length. The catheter segment 110has an arc radius R110 and an arc length L110, the catheter segment 120has an arc radius R120 and an arc length L120, the catheter segment 130has an arc radius R130 and an arc length L130, and the catheter segment140 has an arc radius R140 and an arc length L140. In variousembodiments, the various arc radii and arc lengths are scaled up or downto allow for different sized patient physiology. In some embodiments,the radius R120 and the radius R130 are the same or nearly the same. Inthis situation, the catheter segment 120 and the catheter segment 130merge into a single, generally longer middle segment 150 having an arcradius R150 and an arc length L150.

In various embodiments, different radii and arc lengths can be used. Forexample, in various embodiments, the radius R110 is from about 3 inchesto about 4 inches and the arc length L110 is from about 2 inches toabout 4 inches; the radius R120 is from about 1.2 inches to about 1.8inches and the arc length L120 is from about 0.1 inches to about 0.7inches; the radius R130 is from about 2.2 inches to about 3.7 inches andthe arc length L130 is from about 1.4 inches to about 3.3 inches; andthe radius R140 is from about 1 inch to about 1.5 inches and the arclength L140 is from about 0.7 inches to about 2 inches. In theembodiments wherein the segments 120 and 130 are combined into a segment150, the combined radius R150 is from about 2.2 inches to about 3.0inches and the arc length L150 is from about 2.2 inches to about 3.0inches. The length l of the end portion 160 is from about 0 (i.e., endportion 160 is not present) to about 1.9 inches.

According to one embodiment of the present invention, the distal portion106 is generally J-shaped such that the terminal portion 160 isgenerally parallel to the proximal portion 102. According to anexemplary catheter having a J-shaped distal portion, the segment 110 iscurved so as to have a radius R110 of about 3.88 inches and an arclength L110 of about 3.95 inches, the segment 120 is curved so as tohave a radius R120 of about 1.41 inches an arc length L120 of about 0.4inches, the segment 130 is curved so as to have a radius R130 of about2.93 inches an arc length L130 of about 2.4 inches, the segment 140 iscurved so as to have a radius R140 of about 1.18 inches and an arclength L140 of about 1.28 inches, and the end portion 160 has a length lof about 0.95 inches.

Table 1 below shows dimensions of radius of curvature and arc length forseveral exemplary embodiments of a catheter 100 according to the presentinvention, including examples wherein the segments 120 and 130 arecombined into a single segment 150.

TABLE 1 R110 L110 R120 L120 R130 L130 R140 L140 I 1 3.88 3.95 1.41 0.42.93 2.4 1.18 1.28 0.95 2 3.88 3.95 1.63 0.57 3.5 1.53 1.0 1.4 0.5 R110L110 R150 L150 R140 L140 I 3 3.88 3.27 2.47 2.7 1.33 1.74 1.41

FIG. 3 illustrates a catheter 200 according to another embodiment of thepresent invention. As shown in FIG. 3, the catheter 200 has a proximalportion 202 and a distal portion 206. Again, the proximal portion 202 isadapted for manipulation by a surgeon to advance the distal portion 206into the patient's anatomy to access the coronary sinus 56. As shown inFIG. 3, the distal portion 206 includes a first arc or catheter segment210, which is coupled to a second arc or catheter segment 220. Extendingfrom the distal end of the catheter segment 220 is a third arc orcatheter segment 230, which is coupled to a fourth arc or cathetersegment 240. Extending from the distal end of the catheter segment 240is a generally straight end or terminal segment 260 having a length l.In this embodiment, the overall shape of the distal portion 206 is aclosed arc in which the distal end 206, if extended, would intersectwith the catheter proximal portion 202. In other words, the overallcurvature of the distal portion 206 exceeds 180 degrees of rotation.

In this embodiment, the segment 210 is curved so as to have an arcradius R210 of from about 3.5 to about 4 inches and an arc length L210of from about 3 to about 4 inches; the segment 220 is curved so as tohave an arc radius R220 of from about 1.3 to about 1.5 inches and an arclength L220 of from about 0.1 to about 0.2 inches; the segment 230 iscurved so as to have an arc radius R230 of from about 2.4 to about 2.7inches and an arc length L230 of from about 2.8 to about 3.2 inches; thesegment 240 is curved so as to have an arc radius R240 of from about 1to about 1.5 inches and an arc length L240 of from about 1.5 to about2.2 inches; and the end portion 260 has a length l of from about 0 toabout 1 inch.

Table 2 below shows dimensions of radius of curvature and arc length forseveral exemplary embodiments of a catheter 200 according to the presentinvention, including examples wherein the segments 220 and 230 arecombined into a single segment 250 having an arc radius R250 and an arclength L250.

TABLE 2 R210 L210 R220 L220 R230 L230 R240 L240 I 1 3.88 3.95 1.41 0.142.54 3.06 1.27 1.72 0.4 R210 L210 R250 L250 R240 L240 I 2 3.88 3.27 2.472.78 1.07 1.92 0.52 3 3.88 3.27 2.47 2.78 1.07 1.85 1.49 4 3.88 3.272.47 2.7 1.07 1.75 1.05

FIG. 4 illustrates a catheter 300 according to another embodiment of thepresent invention. The catheter 300 has a proximal portion 302 and adistal portion 306. As shown in FIG. 4, the distal portion 306 includesa first arc or catheter segment 310, which is coupled to a second arc orcatheter segment 320. Extending from the distal end of the cathetersegment 320 is a third arc or catheter segment 330, which is coupled toa fourth arc or catheter segment 340. Extending from the distal end ofthe catheter segment 340 is a generally straight end or terminal segment360 having a length l. As further shown in FIG. 4, the overall shape ofthe distal portion 306 is an open arc, in which the distal end 306, ifextended, would extend away from the catheter 300. In other words, theoverall curvature of the distal portion 306 is less than 180 degrees ofrotation.

In this embodiment, the segment 310 is curved so as to have a radiusR310 of from about 3 to about 4 inches and an arc length L310 of fromabout 3.6 to about 4.4 inches; the segment 320 is curved so as to have aradius R320 of from about 1.2 to about 1.6 inches and an arc length L320of from about 0.2 to about 0.4 inches; the segment 330 is curved so asto have a radius R330 of from about 2.5 to about 3.5 inches and an arclength L330 of from about 2.8 to about 3.4 inches; and the segment 340is curved so as to have a radius R340 of from about 1 to about 1.5inches and an arc length L340 of from about 0.8 to about 1.2 inches. Theend portion 360 has a length l of from about 0 to about 1.5 inches.

Table 3 below shows dimensions of radius of curvature and arc length forseveral exemplary embodiments of a catheter 300 according to the presentinvention, including examples wherein the segments 320 and 330 arecombined into a single segment 350 having a radius R350 and an arclength L350.

TABLE 3 R310 L310 R320 L320 R330 L330 R340 L340 I 1 3.88 3.95 1.41 0.32.97 3.1 1.3 0.91 0.97 R310 L310 R350 L350 R340 L340 I 2 3.05 2.15 3.272.57 1.35 1.37 0.91 3 3.88 3.27 2.47 2.78 1.07 0.93 1.81 4 3.88 3.272.47 2.78 1.07 0.93 1.3

Referring generally to FIG. 1, the shaft 48 of the catheter 10 may bemade from any material generally known in the art, including for examplePEBAX® and urethane. In one example, the catheter 10 is formed bymelting PEBAX® under a shrink tube, stripping the shrink tube,installing a shape mandrel and heating it to a forming temperature. Inone embodiment, a pre-shaped wire or stylet is inserted into a lumen inthe mandrel to give the mandrel the desired shape. The catheter 10 isthen placed over the mandrel and heated to allow it to take the desiredshape. In one embodiment, for example, the catheter 10 is heated atabout 280° Fahrenheit for about 20 minutes. Upon cooling the catheter 10will retain the shape of the mandrel. An alternate construction includesa multi-layer design. In one embodiment, the shaft 48 includes a supportmaterial such as steel braiding, for example.

The distal portion 52 also includes a series of sections havingdifferent lengths. These sections are made of a thermoplastic materialsuch as a thermo polymer having a varying durometer or degree ofhardness. According to one embodiment, the hardness of the distalportion 52 softens proximally to distally, such that the distal portion52 has a lower degree of hardness than the proximal portion 50. In oneembodiment, any thermoplastic material is used to form the catheter 10.

Guide catheters are employed in a variety of applications. One exemplaryapplication involves a method of gaining access to the coronary sinus56. The coronary sinus access method involves inserting the catheter 100through an incision in an appropriate access vessel. Common accessvessels include the subclavian veins, the internal jugular veins, andthe brachiocephalic veins.

It will be appreciated by those skilled in the art that the pre-formedshape allows the distal portion 106 to be steered by rotating theproximal portion 102. The ability to rotationally steer the distalportion 106 provides a guide catheter 100 according to the presentinvention useful in locating specific vascular features. In particular,the configuration of the pre-formed distal portion 106 enables the guidecatheter 100 to find support from the walls of the superior vena cava20, rather than the right atrium 14, during insertion procedures. Thisfeature is advantageous because the size, configuration and location ofthe right atrium 14 tends to vary widely from patient to patient,particularly in patients having diseases of the heart. In contrast, thesuperior vena cava 20 tends to remain relatively constant in size andlocation. Thus, less time need generally be spent on locating thecoronary sinus ostium 54 when utilizing the superior vena cava 20 forsupport than when relying on the right atrium 14. A guide catheter 100according to the present invention thus advantageously provides areliable and efficient tool for accessing the coronary sinus 56 via theright atrium 14.

FIG. 5 shows the guide catheter 100 of FIG. 2 assembled with an innercatheter 170. The inner catheter 170 has a preformed distal end 172, sothat relative rotation and extension of the inner catheter 170 and guidecatheter 100 provides the distal end 152 of the guide catheter 100 withan adjustable range of two- and three dimensional shapes. An example ofthis is described is U.S. Patent Publication 2003/0144657, which ishereby incorporated by reference. Furthermore, as illustrated, extensionof the distal end 172 of the inner catheter 170 beyond the distal end152 of the guide catheter shaft 148 results in a catheter assemblyhaving a compound curvature.

FIG. 6 shows the catheter assembly of FIG. 5 deployed in the heart 12.The curvature of the guide catheter 100 provides easy access through thecoronary sinus ostium 54 from the right atrium 14. The inner catheter170 is advanced through the guide catheter shaft 148 and longitudinallyextended to sub-select a branch of the coronary sinus 56. The guidecatheter 100 is then advanced over the inner catheter 170 into the sidebranch. The inner catheter 170 is removed by proximally sliding theinner catheter 170 out of the catheter 100.

Optionally, a guide wire 180 may also be employed in conjunction with aguide catheter according to the present invention (See FIG. 5). Theguide wire 180 is often introduced through the access vessel into theright atrium 14. The guide catheter 100 is advanced over the guide wire180 into the right atrium 14 through the superior vena cava 20, forexample. Typically, the catheter 100 is then deployed over the guidewire 180, the guide wire 180 helping to provide support and guidance forthe catheter assembly 100 as it is advanced into the right atrium 14.From the right atrium 14, the catheter 100 is used to effectively locateand cannulate the coronary sinus 56.

After the guide catheter shaft 148 is seated in the coronary sinus 56,the guide catheter shaft 148 can be used to introduce a payload into theheart 12. If the guide wire 180 or inner catheter 170 were used, theymay also be removed. The payload in one exemplary embodiment is a pacinglead. Once the payload has been successful seated, the guide catheter100 can then be removed. Assuming the payload is to remain in the heart,the guide catheter 100 is moved in a proximal direction over the payloaduntil the guide catheter 100 is removed from the access vessel.

FIG. 7 illustrates a method 400 of employing a guide catheter tocannulate a vessel of the heart according to one embodiment of thepresent invention. A guide catheter in accordance with the presentinvention is advanced into the superior vena cava from the leftsubclavian vein (block 410). The guide catheter is advanced into theright atrium, finding support from the walls of the superior vena cava(block 420). The guide catheter is advanced until the distal tip crossesthe tricuspid valve (block 430). The guide catheter is torqued 90degrees counterclockwise to maneuver the distal tip into the same planeas the coronary sinus ostium (block 440). The torque is maintained whilepulling the guide catheter back into the right atrium (block 450).Finally, torque is maintained and the guide catheter is advanced forwardinto the coronary sinus ostium (block 460).

FIG. 8 illustrates another method 500 of employing a guide catheter inconjunction with an inner catheter and a guide wire to cannulate avessel of the heart according to another embodiment of the presentinvention. The guide catheter is advanced into the superior vena cavafrom the left subclavian vein and into the right atrium, using the wallsof the superior vena cava for support (block 510). The guide catheter isadvanced until the distal tip crosses the tricuspid valve, then torqued90 degrees counterclockwise to maneuver the distal tip into the sameplane as the coronary sinus ostium (block 520). Torque is maintainedwhile pulling the guide catheter back into the right atrium (block 530).An inner catheter is advanced through the guide catheter, beyond thedistal tip of the guide catheter, and torqued to locate the coronarysinus ostium (block 540). A guide wire is advanced through the innercatheter and the inner catheter and guide wire are alternately advancedinto a side branch of the coronary sinus ostium (block 550). Finally,the guide catheter is advanced over the inner catheter into the sidebranch of the coronary sinus ostium (block 560).

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. Accordingly, the scope of the present invention is intendedto embrace all such alternatives, modifications, and variations as fallwithin the scope of the claims, together with all equivalents thereof.

1. A guide catheter for cannulating a coronary sinus from a superiorvena cava, the guide catheter comprising: a flexible elongate shafthaving a proximal portion, a middle portion and a distal portionterminating in a distal tip, the distal portion having a preformed shapeconfigured such that the distal portion of the shaft is supported on awall of the superior vena cava when locating an ostium of the coronarysinus with the distal tip, the preformed shape of the distal portionlying in a single plane and defined at least by: a first arc adjacentthe middle portion and having a first arc radius ranging fromapproximately 3 to approximately 4 inches; a second arc distallyadjacent the first arc and having a second arc radius ranging fromapproximately 1.2 to approximately 1.8 inches; a third arc distallyadjacent the second arc and having a third arc radius ranging fromapproximately 2.2 to approximately 3.7 inches; a fourth arc distallyadjacent the third arc and having a fourth arc radius ranging fromapproximately 1 to approximately 1.5 inches; and a generally straightterminal portion adjacent the fourth arc and having a length rangingfrom approximately 0.4 to approximately 1.81 inches.
 2. A guide catheterfor cannulating a coronary sinus from a superior vena cava, the guidecatheter comprising: a flexible elongate shaft having a proximal portionand a distal portion terminating in a distal tip, the distal portionhaving a preformed shape configured such that the distal portion of theshaft is supported on a wall of the superior vena cava when locating anostium of the coronary sinus with the distal tip, the preformed shape ofthe distal portion lying in a single plane and having an overall lengthfrom approximately 4.2 to approximately 11.81 inches and including atleast: a first arc segment having a first arc radius ranging fromapproximately 3 to approximately 4 inches; a second arc segment having asecond arc radius ranging from approximately 1.2 to approximately 1.8inches; a third arc segment having a third arc radius ranging fromapproximately 2.2 to approximately 3.7 inches; and a generally straightterminal portion distal to the third arc segment and having a length ofup to approximately 1.81 inches.
 3. The guide catheter of claim 2,wherein the first arc radius ranges from approximately 3.5 toapproximately 4 inches.
 4. The guide catheter of claim 3, wherein thefirst arc radius is approximately 3.88 inches.
 5. The guide catheter ofclaim 2, wherein the first arc segment has a first arc length rangingfrom approximately 2 to approximately 4 inches.
 6. The guide catheter ofclaim 2, wherein the first arc radius is approximately 3.88 inches andwherein the first arc segment has a first arc length of 3.95 inches. 7.The guide catheter of claim 2, wherein the first arc radius isapproximately 3.88 inches and wherein the first arc segment has a firstarc length of 3.27 inches.
 8. The guide catheter of claim 2, wherein theflexible elongate shaft further includes a deflection location disposedbetween the proximal portion and the preformed distal portion.
 9. Theguide catheter of claim 2, wherein a hardness value of a thermoplasticmaterial forming the distal portion decreases from proximally todistally.
 10. The guide catheter of claim 2, wherein the first, secondand third arc segments are arranged such that the terminal portion isoriented generally parallel to the proximal portion of the shaft. 11.The guide catheter of claim 2, wherein the shaft is configured toslidably receive an inner catheter configured for sub-selecting a branchof the coronary sinus.
 12. A guide catheter for cannulating a coronarysinus from a superior vena cava, the guide catheter comprising: aflexible elongate shaft having a proximal portion and a distal portionterminating in a distal tip, the distal portion having a preformed sizeand shape configured so that the distal portion of the shaft issupported on a wall of the superior vena cava during insertion of thedistal portion into the coronary sinus, the preformed shape of thedistal portion lying in a single plane and having an overall length offrom approximately 4.2 to approximately 11.81 inches and including atleast: a first arc segment having a first arc radius ranging fromapproximately 3 to approximately 4 inches; a second arc segment having asecond arc radius ranging from approximately 1.2 to approximately 1.8inches; a third arc segment having a third arc radius ranging fromapproximately 2.2 to approximately 3.7 inches; and a generally straightterminal portion distal to the third arc segment and having a length ofup to approximately 1.81 inches.
 13. The guide catheter of claim 12,wherein the flexible elongate shaft further includes a deflectionlocation disposed between the proximal portion and the preformed distalportion.
 14. The guide catheter of claim 12, wherein a hardness value ofa thermoplastic material forming the distal portion decreases fromproximally to distally.
 15. The guide catheter of claim 12, wherein thefirst, second and third arc segments are arranged such that the terminalportion is oriented generally parallel to the proximal portion of theshaft.
 16. The guide catheter of claim 12, wherein the shaft isconfigured to slidably receive an inner catheter configured forsub-selecting a branch of the coronary sinus.